Hi there good people.
Quick disclaimer.
I am one of those old grumpy people what whines and complains about whatever is new. Then I'm dragged (kicking and screaming) to try said new thing and end up (begrudgingly) loving it.
I haven't tried neither TypeScript, Dart or CoffeeScript but before diving in I would love to hear honest opinions from people actually using it. Particularly TypeScript.

Admittedly I haven't used it much, but it strikes me as a superset of JavaScript for C# developers and a slight rehash of JScript. This should be no surprise, as it is a Microsoft initiative and doubtless enables .net developers to achieve a higher level of full stack productivity.
While its compatibility with Visual Studio's debugger is excellent and it can in theory output highly performant JS, I have to say that, having myself approached C# only after JS, and having a better knowledge of JS than the former, I don't really see the point in writing typesafe code that's eventually transpiled for a non-typesafe interpreter.

While I'd agree its a natural stepping stone for c# devs that's not it's origins. Typescript is a superset of JavaScript and the roots of its optional static typing where laid down many years ago with ActionScrript and the abandoned ES4 spec.

Thanks. You do make some valid points and would like to pick your brain a bit further :-)
a) What about organisation? Did you feel like it easier to work on a team and share code?
b) Did you had any problems with the compiled code?

Hello! So sorry I didn't write back. And thank you lordhanson - I didn't know that, but it makes perfect sense. To answer your question, coffee:
a) I did, yes, as statically typed code is much easier to reason about. TypeScript is naturally a little more verbose than plain JavaScript, but what it lacks in brevity it more than makes up for with clarity.
b) Nope, no problems; I use Browserify a lot so tsify was a natural choice of tooling for me. But there are many options available to support whatever you're using to compile modules.
I may well end up using TS exclusively going forward, especially due to the quality of code produced using TS + ES6. It's a Microsoft-backed project and seems it's around to stay, so my conclusion is that it's well worth taking it up if it piques your curiosity sufficiently after one or two tries.

TypeScript: Hopeful that better static type support will arrive in JS Proper. Not terribly impressed with it as a compile to language. I prefer something with less syntax noise, not more. CoffeScript is a step in the right direction for me.

I've been using TypeScript now for over 2 years and have to say I love it. Being able to use future JavaScript language features years before they are common in browsers is a massive win. But the optional type annotations are a must for apps of scale. We have a large code base built entirely using TypeScript and there's 7 Ui devs all working on it in parallel. The typing info makes that process far more resilient and allows us to refactor core parts of the application quicker and safer.
You still need unit tests, but a compiler is a good friend and shouldn't be under valued. 👍